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NE555: Can I pull down the OUT pin?

R.Fukunaga
Expert 2525 points
Part Number: NE555

Hi all,

The OUT pin is pulled up by the Rl resistor.

Is it possible to pull down the OUT pin and use NE555?

I would appreciate it if you could tell me.

Best Regards,

Ryusuke

  • +1
    TI__Mastermind 25425 points

    Hello Ryusuke, 

    Rl can be tied to either the positive rail or ground. The resistor isn't required for operation. 

    Let me know if I can be of further assistance. 

    Best Regards, 

    Chris Featherstone

  • +1
    TI__Genius 13485 points

    Hi Ryusuke,

    To add to Chris' response, the OUT pin can both sink and source current; this is described in the section of the EC table shown below:

    Note that output voltages are specified for both positive and negative current.

    The RL in the schematic above is just representing a load resistance, it isn't required to achieve a high output voltage (like what would be the case in an open-collector output). 

    Hope this helps.
    Mike